Sausages and pork chops could also be off the menu if the disease spreads to Britain’s pigs (Picture: Alamy)

The bacon butty is under threat from a deadly pig virus.

Sausages and pork chops could also be off the menu if a disease that has killed 4million porkers in America spreads to Britain.

Porcine epidemic diarrhoea virus is harmless to humans but kills nearly all piglets that get it and makes older pigs get sick and lose weight.

If it arrives here it will have a ‘devastating effect, damaging breeders’ livelihoods and pushing pork prices up, experts warn.

‘It’s impossible to overstate the damage it would cause,’ said vet Derek Armstrong, of pig farmers’ group BPEX.

‘The evidence from the US is that it’s so infectious, just one infected pig is all it would take to start an epidemic that could kill as much as ten per cent of our national herd.’

It’s thought the virus may be helped to spread by the practice of giving piglets the blood of slaughtered swine to eat, as a way of boosting growth.

A blood-derived feed known as spray-dried porcine plasma has been found to contain PEDV but it is not clear whether the pigs can catch the virus by eating it.

Although manufacturers insist SDPP is safe, industry associations are warning farmers to ‘take every precaution’ when using it.

Penny Johnston of the NFU said pork producers needed to do everything they could to stop the virus reaching our shores. ‘I don’t believe the feed is the only potential source of it entering the country,’ she said.

‘Farmers have to be careful of equipment coming on to their land, of people coming from areas where the disease has been and also of pig movements. We have to be very vigilant and aware.’